Apparatus for stacking and registering sheets prior to an operation performed on a collected set of sheets, such as stapling, is well known in the art. Generally, in such apparatus, collected sheets are registered by moving one or more jogging elements against an edge of the stack to align the opposite edge of the stack with a registration surface, defined either by a fixed guide or by a movable registration gate. Since sheets are continually being fed to the stack, and since it is desirable to jog the stack as it is being formed, the jogging elements must be moved in such a manner as not to interfere with the sheet-feeding operation, particularly if the jogging elements act against the trailing edge of a stack. This is generally accomplished by mounting the jogging element for movement from a rest, or home, position beneath the stack-receiving surface along a path which extends upwardly through a slot or the like formed in the receiving surface and then generally horizontally against the desired edge of the stack. One such jogging mechanism is shown, for example, in U.S. Pat. No. 4,073,391, issued to O'Brien et al.
While the jogging mechanism shown in the patent to O'Brien et al is capable of jogging sheets against a leading-edge registration gate without interfering with the feeding of additional sheets to the stack, it nevertheless retains several undesirable features of operation. In particular, the assembly for actuating the trailing-edge jogging element of O'Brien et al is relatively complicated in its construction and does not readily permit variation in the placement of the jogging mechanism (other than to accommodate sheets of varying lengths) or the conjoint use of several such jogging mechanisms without unduly complex coupling arrangements.